Influence of Hydrogeological Factors on Exposure to Emerging Contaminant in Karst Environments

摘要

Providing 20-25% of the global population water needs, karst aquifers are extremely productive groundwater systems that develop in soluble geologic formations. The same characteristics that make karst aquifers highly productive and important freshwater resources for human consumption also impart a high vulnerability for contamination. As a consequence, these aquifers can serve as significant routes of contaminant exposure. Emerging contaminants, including phthalates, are of particular concern because they can easily enter karst groundwater and move toward areas of potential exposure to human. Many of these contaminants are known endocrine disruptors and potential precursors of adverse reproductive outcomes. Previous studies in the karst region of northern Puerto Rico have shown significant presence of phthalates in groundwater and tap water. This work evaluates potential correlations between hydrogeological factors, diethylhexyl phthalate (DEHP) contamination, and potential exposure at the tap water point of use. Geographic Information Systems technologies and statistical models are applied to attain these objectives. The analysis incorporates data gathered from regulatory agencies and current groundwater and tap water samples collected from homes. Results show widespread distribution of DEHP in both groundwater and tap water, suggesting that contamination comes from multiple sources. Spatial variability of DEHP in groundwater is significantly influenced by hydrogeological factors, reflecting the importance of groundwater transport from sources of contamination to potential points of exposure. Spatial correlation analysis indicates that association between tap water and groundwater contamination depends on spatial location and time. Though groundwater serves as route of contamination to tap water sources, additional sources of contamination from the water distribution system increases the presence of phthalates in tap water and the potential for exposure.